The invention relates to spatial and shading error correction systems, and particularly to a manually-operated spatial and shading error measurement and correction system which performs point-by-point error correction of a video picture.
Various systems are presently known for performing spatial and shading error corrections using analog and/or digital techniques. The systems thus range from analog signal sources wherein correction is performed manually or automatically by adding various sawtooth, parabola, etc., waveforms to the basic horizontal and vertical deflection waveform, to digital schemes for precisely measuring the errors at selected sample points in a video picture, for performing an integration process on the resulting error samples, and for continually generating error correction during the camera operating mode. It follows that the various systems encompass widely-ranging degrees of complexity and different degrees of manual participation in order to perform the required error measurement and/or correction processes.
Due to the rapidly increasing application of digital techniques in the video recording field because of the inherent advantages of ease and speed in data handling and storage, compactness, low cost, etc., video cameras are being developed which employ digital techniques throughout their design. Digital techniques allow a much greater degree of compactness and thus portability in video cameras without compromising the quality of the video picture. Since digital techniques also facilitate the use of automation, various highly sophisticated and totally automated error measurement and error correction systems are being contemplated by those in the field. These latter systems, particularly in the case of the error measurement systems, incorporate off-line plug-in automatic setup units, remotely-located from the camera head unit, which provide highly accurate error detection schemes but which correspondingly add substantially to the cost of a fully automated precision error correction system.